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Spill Season Update




Metadata for 2019 Voluntary Spill Web-page:

 

  • Click here to download a copy of the 2019 Voluntary Spill Metadata.


In accordance with the 2019 Fish Operations Plan (FOP), voluntary spill was initiated at the Snake River Projects at 0001 hours on April 3, 2019 and will run through August 31, 2019.  Spring spill operations in the Snake River will run from April 3rd to June 20th and summer spill operations will run from June 21st through August 31st.  The 2019 FOP calls for the following spill levels at the Federal Snake River Projects:

 

Project

Spring Spill

Spring Spill

Summer Spill

 

Gas Cap Spill*

(16 Hours)

Performance Standard

(8 Hours)

24 hour spill

Lower Granite

120% Gas Cap

20 Kcfs

18 Kcfs

Little Goose

120% Gas Cap

30%

30%

Lower Monumental

120% Gas Cap

30 Kcfs (bulk pattern)

17 Kcfs

Ice Harbor

120% Gas Cap

30%

30%

 

In accordance with the 2019 FOP, voluntary spill is to be initiated at the Middle Columbia projects at 0001 hours on April 10, 2019 and will run through August 31, 2019.  Spring spill operations in the Middle Columbia River will run from April 10th to June 15th and summer spill operations will from June 16th through August 31st.  The 2019 FOP calls for the following spill levels at the Federal Middle Columbia River Projects:

 

Project

Spring Spill

Spring Spill

Summer Spill

 

Gas Cap Spill*

(16 Hours)

Performance Standard

(8 Hours)

24 hour spill

McNary

120% Gas Cap

48%

57%

John Day

120% Gas Cap

32%

35%

The Dalles

120% Gas Cap

40%

40%

Bonneville

120% Gas Cap

100 Kcfs

95 Kcfs

 

Per the 2019-2021 Spill Operations Agreement between the Action Agencies and the States of Oregon and Washington and the Nez Perce Tribe, Gas Cap spill in spring of 2019 will be managed to a 120% TDG standard in the tailrace only.  Summer spill in 2019 will be managed to a 120% tailrace or 115% forebay TDG standard, whichever is more restrictive.

 

 

Estimation of FOP Spill

All projects have a minimum powerhouse flow requirement.  The table below provides the range of minimum powerhouse requirements for each project, followed by the assumed minimum for the graphs (in parentheses).  The assumed minimum requirements include project specific miscellaneous flows (e.g., adult fishways, etc.).

 

Project

Minimum Powerhouse Flow (Kcfs)

Lower Granite

11.8-12.9 (12)

Little Goose

11.3-11.8 (11.5)

Lower Monumental

11.1-12.3 (12)

Ice Harbor

8.4-10.1 (10)

McNary

50-60 (55)

John Day

50-60 (51.2)

The Dalles

50-60 (56)

Bonneville

30-40 (42)

 

At low flows, the FOP spill amounts cannot always be provided along with minimum powerhouse flows.  In this instance, all estimates of FOP spill (i.e., red lines on FPC graphs) are adjusted for assumed project specific powerhouse minimum requirements using the following criteria:

 

            If Total Flow > FOP + PH Min then FOP = FOP

            If Total Flow < FOP + PH Min then FOP = Total Flow – PH Min

 

 

12-Hr Average TDG

Per the 2019-2021 Spill Operations, Oregon and Washington will be using the same methodology for estimating the 12-hour average TDG for the spring spill season.  This 12-hour average in the spring season will be based on the 12 highest hourly TDG measurements in a single calendar day (not necessarily consecutive). 

 

However, for the summer spill season, Oregon and Washington will have two different methodologies for estimating the 12-hour average TDG.  For Oregon, the 12-hour average will be based on the 12 highest hourly TDG measurements in a single calendar day (not necessarily consecutive).  For Washington, the 12-hour average is based on rolling 12-hour averages.  The highest of the rolling averages is what is reported as the 12-hour average for a given day.  The location of a TDG monitor and/or type of monitor will dictate which of these methodologies is used for compliance monitoring in the summer.  Below is a table of which methodology or methodologies will be used for each monitor. 

 

TDG Monitor

12-Hr Average TDG Methodology Used

Lower Granite Tailrace

Washington

Little Goose Forebay

Washington

Little Goose Tailrace

Washington

Lower Monumental Forebay

Washington

Lower Monumental Tailrace

Washington

Ice Harbor Forebay

Washington

Ice Harbor Tailrace

Washington

McNary Forebay

Washington

McNary Tailrace

Greater of Washington or Oregon

John Day Forebay

Washington

John Day Tailrace

Greater of Washington or Oregon

The Dalles Forebay

Washington

The Dalles Tailrace

Greater of Washington or Oregon

Bonneville Forebay

Washington

Bonneville Tailrace (CCIW)

Greater of Washington or Oregon

 

 

*Spill to the Gas Cap

The 2019 FOP calls for spill to the 120% Gas Cap for up to 16-hours per day at all eight FCRPS projects.  Spill to the 120% gas cap means to spill to a volume of water that achieves, but does not exceed, the total dissolved gas (TDG) waivers.  In spring 2019, these waivers are to a 120% TDG standard in the tailrace only.  To assess whether the FOP is being implemented, spill should be evaluated relative to whether the 120% TDG is being met in the tailrace when the 120% Gas Cap Operation is being implemented.  The FPC graphs provide the hourly TDG measurements from the tailrace monitors in order to facilitate these evaluations. 

 

The US Army Corps of Engineers (COE) develops daily levels of maximum spill that the COE estimates will not exceed the 120% tailrace TDG criteria.  These estimates “spill caps” are provided to the project operators as maximum spill levels.  The estimates “spill caps” presented in the graphs are taken directly from the TMT website (http://pweb.crohms.org/tmt/documents/ops/spill/caps/) and are typically updated in the afternoon.  The COE’s assessment of meeting daily Gas Cap spill under the FOP is based on whether the project spills to the estimated “spill caps”, not necessarily whether TDG met, but did not exceed, the 120% standard. 

 

 

Note:

Spill at some projects varies relative to flow, therefore the scale of the y-axes may be different for each project and may change from week to week or even day to day at an individual project.